<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<script>
			var num1 =parseInt(prompt("请输入第一个数字："));
			var ysf =prompt("请输入运算符：1.+  2.- 3.* 4./");
			var num2 =parseInt(prompt("请输入第二个数字："));
			
			if(ysf=="1"){
				document.write(num1+num2);
			}else if(ysf=="2"){
				document.write(num1-num2);
			}
			else if(ysf=="3"){
				document.write(num1*num2);
			}
			else if(ysf=="4"){
				document.write(num1/num2);
			}
			else{
				document.write("结果错误！")
			}
		</script>
	</body>
</html>
